Heat exchange apparatus



june 29, Q RElGART ET AL 2,085,041

v HEAT EXCHANGE APPARATUS Filed May 24, 1935 Patented `lune 29, 1937 UNITED STATES PATENT OFFICE HEAT EXCHANGE APPARATUS New York Application May 24, 1935, Serial No. 23,236

17 Claims.

This invention pertains to heat exchange apparatus and more particularly relates to extended heating surfaces for the tubes of such apparatus and to means for securing the extende surface members to the tubes.

In order that an extended surface member after being4 positioned on a tube may form an ecient means of transferring heat between the extended surface and the tube, it is important that the common or contacting surfaces of the .tube and the extended surface be of essentially the same contour, of ample extent, and that they be held tightly together at all temperatures which the tube and extended surface must withstand. A common means of providing a tube with an extended surface has been to shrink or force a ring or disc, which forms the extended surface, on to the tube.

When a ring or disc is shrunk onto a tube. and

the assembly is heated, the ring or disc expands and contracts simultaneously with the tube. If the coemcient of expansion of the ring is less than that of the tube, the ring will grip the tube more tightly when the temperature of the tube and ring is raised. .For this reason, when cast iron extended surface rings are shrunk on steel tubes, the combination forms effective means for transferring heat to the fluid in the tubes from a fluid` of higher temperature which contacts with the rings for the reason that the coeicient of expansion of the cast iron rings is less than that of the steel tubes. Where, however, metals other than cast iron are utilized for the extended surface members to the end that the weight of the extended surface members may be reduced, it has been found that'such lighter metals or alloys, particularly aluminum and its alloys, do not remain in good thermal contact Vwith the tubes when subjected to heat because 40 such lighter metals have' higher coeflicients of expansion than the steel tubes. In consequence, the ring or disc grips the tube less tightly upon heating, which makes it necessary to provide an unduly great diiference between the temperature 45 of the extended surface members and of the tubes in order to transfer heat between the rings and the tubes in commercialfamounts.

` The present invention provides readily applied and emcient means for attaching to tubes ex- 50 tended surface members having higher coeicients of expansion than the tubes to which they are secured, so that the thermal conductivity between the extended surface members and the 55 tubes will not be reduced or materially lessened when .the members andl tubes are subjected to high temperatures. Y

The invention further provides effective means for shielding the means for securing the extended surface members to the tubes to protect the securing means against any corrosive action of the heating medium.

The invention will be understood from the following description when considered in connetion with the accompanying drawing forming a part thereof and in which:

Fig. 1 is a longitudinal sectional view of part of a-tube included in vheat transfer apparatus and provided with extended surface members secured to the tube in accordance with the present invention;

Fig. 2 is a sectional View on a reduced scale, taken on line 2-2 of Fig. 1; and

Fig. 3 is a partial sectional view, taken on line 3-3 of Fig. 2.

Like characters of reference refer to the same or similar parts in the several views.

The invention will be described in connection with heat transfer apparatus consisting essentially of steel tubes to which are secured extended surface discs or rings of aluminum or aluminum alloy which are secured to the steel tubes by steel retaining rings or bands having a coeilicient of expansion no greater and preferably less than the coemcient of expansion of the steel tubes. It will be understood, however, that the invention is not limited to these particular metals for the several parts but that the invention is applicable to the securing of extended surface members to tubes in all cases where the coeflcient of expansion ofthe extended surface members is greater than that of the tubes.

In the drawing, reference character l0 designates a steel tube forming part of a tubular heat exchange apparatus. 'Ihe extended surface members secured to the outer cylindrical surface of the tubes, in the-embodiment shown, consist of a plurality of separate discs II of aluminum or aluminum alloy. Each of the discs Il is provided with an annular liange or hub Il 2 which extends radially outwardly from one side of the inner peripheral portion of the disc. The inner cylindrical surface of the flange l2 is preferably of a diameter slightly less than the outer cylindrical surface of the tube l0 so that the discs may be forced or shrunk onto the tubes. 'I'he radially outer cylindrical surface I3 of each of the flanges I2 is preferably inclined, as shown, outwardly from the side.- of the disc from which the flange extends and toward the axis of the 2 A accenti tube. The retaining rings I lt are made of steel having a coemcient of expansion equal to or somewhat'less than that of the steel tube I@ and are provided with a tapering or inclined in- 5 ner cylindrical surface which cooperates with the inclined surface I3 of flange I2. The diameter of the inner cylindrical surface of the retaining rings is preferably somewhat less than that of the surface I3 of flange i2 so that the rings may l be driven on to the flanges I2 to provide a good driving fit. o

If desired, the inner cylindrical portion i5 of the discs II and the flanges I2 maybe cut or formed to provide a plurality of slots I6 preferably disposed more or less uniformly about the hub of the discs. In the embodiment shown, these slots extend from the inner cylindrical surface of the discs toward the outer peripheries thereof but only to a point just outwardly of the outer cylindrical surface of the retaining rings I4. It will be understood however that these slots may extend outwardly toward the outer peripheries of the discs Il as far as desired and in some instances the slots may extend entirely outwardly to the periphery, thereby completely severing the discs in one or more places. These slots provide the discs or the hub portions thereof with a degree of resiliency they would not otherwise possess and facilitate the securing of the discs to the tubes and the maintenance of good thermal consuch exposure, means are provided for shielding the retaining ring from contact with such fluid. In the form of the invention shown, such means consists of an annular flange I1 which extends outwardly from the same side of the discs I l from -which the ange 4I2 extends. Flange I1 is spaced radially outwardly from the flanges I2, a distance which is suiiicient so as not to interfere with the application of the retaining rings I4. As shown, the flange orshroud I1 is formed integrally with the disc Il, but if desired, it may be made independent of the disc and thereafter secured thereto, or it may be retained in position by contact with adjacent discs between which it is disposed. The flange l1 isproportioned so that it fits snugly intolan annular recess I8 of the adjacent disc Il with which it comes in contact, or in lieu ofthis arrangement, the danse may be proportioned so that its end will come into firm contact with the adjacent disc and thereby prevent the access of fluid on the outside of the tubes I0 tothe retaining rings.

An annular abutment I9 may be provided which extends from the side of the disc opposite that from which the flanges I2 and I1 extend, and which is disposed and proportioned with respect to the disc so that it contacts the retaining ring s M when the latter is in position and thereby maintains it in such position. v l

The extended surface members IlA are driven onto the tubes I0 in an axial direction or are shrunk thereon individually. After a disc has been driven onto or shrunk in position on a tube, the retaining ring is driven onto and over the flange l2. The cooperating conical surfaces of the flange I2 and ring I4 forces the inner cylindrical surface of the member IIr into firm contact with the tube I0 to thereby lessen the resistance to the flow of heat between the contacting surfaces of the tube and the extended surface member to a minimum. When the tubes and the extended surface mem- 5 bers thereon are subjected to higher temperatures, since the members II have a higher coefcient of expansion than the tubes, they tend to separate their contacting surfaces, but any such tendency isA wholly prevented by the retaining 1o rings I which expand no more than, or somewhat less than the tubes l0. With this arrangement it will be perceived that regardless of variations in temperature to which the tubes and their extended surface members are subjected, the l., initially good thermal contact between the tubes and the extended surface members will be maintained at all times and will tend to become better with increases in temperatures.

The form of the invention selected for dis- 20 closure is to be considered as a preferred form only. Variations inthe form, location and arrangement ofthe several parts, as well as the materials thereof, may be effected Without transcending the principles of 'the invention. For instance, the4 cooperating surfaces between the anges I2 'and the retaining rings I4 may be cylindrical or concentric with respect to the axes of the tubes, rather than tapering orconical, as shown in the drawing. Additionally, other "o means may beemployed for protecting the retaining rings against any injurious effects of fluids which may be used with the apparatus in lieu of the form of the shroud disclosed. For example, the exposed area of the retaining rings may be plated or covered ,with some metal or substance which is not affected by the uids used.

It will be understood that no intention is entertained to limit the invention except by the scope of the claims appended hereto. A

What is claimed is:

l. Heat exchange apparatus including a tube, a

disc constituting an extended surface member for the tube having a highercoeiilcient of expansion than the tube and having one or more slots extending radially outwardly from the inner periphery of the member and terminating short of the outer periphery thereof, and means having a coeiicient of expansion no greater than the tube for securing and retaining the member to the tube.

2. Heat exchange apparatus includingA a tube, a disc constituting an extended surface member for the tube having a higher coemcient of expansion than the tube and having a portion engaging the tube, said tube engaging portion having one or more slots therein terminating short of the periphery of the member, and means having a coeflicient of expansion no greater than the tube for engaging said tube engaging portion for securing the member to the tube.v

3. Heat exchange apparatus including a tube, a disc constituting an extended surface member for the tube having a higher coemeient ofl expansion than the tube, means having a coeicient of expansion no greater than the/tube for securing the member to the tube, and means for shielding the securing means from injurious effects of duid passing through the apparatus. y m

4. Heat exchange apparatus including a tube, a disc constituting an extended surface member for the tube having a higher coefficient of expansion than the tube and having a tube engaging ange, an annulus having a coeflicient of expansion ne 75 greater than the tube for engaging said ange for securing the member to the tube, and means for shielding the annulus from injurious effects of uid passing through the apparatus.

5. Heat exchange apparatus including a tube, an extended surface member for the tube having a higher coefficient of expansion than the tube and having a tube engaging iiange, an annulus having a coefficient of expansion no greater than the tube for engaging said ange for securing the member to the tube, and a. shroud integral with said member for shielding the annulus from injurious effects of iiuid passing through the apparatus.

6. Heat exchange apparatus including a tube, an extended surface member for the tube having a higher coefcient of expansion than the tube and having a tube engaging flange, an annulus having a coe'icient of expansion no greater than the tube for engaging said flange for securing the member to the tube, and a shroud integral with said member for shielding the annulus from injurious eiects of fluid passing through the apparatus, said member having a recess for receiving the outer end of the shroud of an adjacent member.

'7. Heat exchange apparatus including a. tube, an extended surface member for the tube having a higher coeicient of expansion than the tube and having a tube engaging iange, an annulus having a coeiiicient of expansion no greater than the tube for engaging said flange for securing the member to the tube, and a shroud integral with said member for shielding the annulus from injurious eects of iiuid passing through the apparatus, the shroud being proportioned so as to engage the adjacent member when positioned on the tube. 8. Heat exchange apparatus including a tube, a disc constituting an extended surface member for the tube, means for securing the member to the tube, and means for shielding the securing means from injurious effects of uid passing i through the apparatus.

9. Heat exchange apparatus including a tube, a disc constituting an extended surface member for the tube, means for securing the member to the tube, and means integral with said member for shielding the securing means from injurious effects of iiuidl passing through the apparatus.

10. Heat lexchange apparatus including avtube,

Y a disc constituting an extended surface member for the tube having a tube engaging flange, an annulus for engaging the ange for securing the member to the tube, and a shroud for shielding the annulus from injurious eiects of fiuid passing through the apparatus.

11. Heat exchange apparatus including a tube, an extended surface member for the tube having a tube engaging ange, an annulus for engaging the flange for securing the member to the tube, and a shroud for shielding the annulus from injurious effects of fluid passing through the apparatus, said member having a portion for engagement with the shroud of an adjacent member.

12. Heat exchange apparatus including a tube, an extended surface member for the tube having a tube engaging portion, means engaging said portion to secure the member to the tube, and a shroud for the first mentioned securing means, said member having a portion for engagement with the securing means and the shroud of an adjacent member.

13. An extended surface member for the tubes of heat exchange apparatus comprising a disc having a tube engaging portion arranged to receive a securing member and a shroud disposed so as to shield the securing member from injurious effects of fluid passing through the apparatus.

14. An yextended surface member for the tubes of heat exchange apparatus comprising a disk having a tube engaging portion arranged to receive a securing member', said portion having one or more slots which terminate short of the outer periphery of the member.

15. An extended surface member for the tubes of heat exchange apparatus comprising a disc having a tube engaging portion arranged to receive a securing member, said portion having one or more slots which terminate short of the outer periphery of the member, and a shroud disposed so as to shield the securing member from injurious effects of iiuid passing through the apparatus.

16. An extended surface member for the tubes of heat exchange apparatus comprising a disc having a tube engaging portion arranged to receive a securing device, said portion having one or more slots which terminate short of the outer peripheryl `of the member, and a shroud disposed so as to shield the securing device from injurious eiects of uid passing through the apparatus, the member being adapted to engage the shroud of an adjacent member.

17. An extended surface member for the tubes of heat exchange apparatus comprising a disc having a tube engaging portion arranged to receive a securing device, said portion having one or more slots which terminate short of the outer periphery of the member, and a shroud disposed so as to shield the securing device from injurious effects of uid passing through the apparatus, the member being adapted to engage theshroud and the securing device of an adjacent member. CHAUNCEY REIGART. JOHN BLIZARD. MARTIN FRISCH. 

